Open operative surgical treatment of arterial trauma has high morbidity and mortality, and can lead to lifelong disability. In 1991, stent grafts were developed as a minimally invasive way to treat arterial aneurysms. Despite numerous advances, however, stent graft placement in the lower extremities is often plagued by restenosis and thrombosis. Frequently, stents implanted in blood vessels restenose within 6 months after implantation, and the early thrombosis rate can vary between 5% and 27%. The restenosis rate of stents placed in long lesions (e.g., greater than 6 cm) in the superficial femoral artery has been as high as 78% after 12 months.
Percutaneous transluminal arterial angioplasty and stenting causes endothelium to denude, which consequently exposes underlying structural components (e.g., collagen, Von Willebrand factor, fibronectin, and laminin). Exposure of these structural components leads to platelet adherence, aggregation, and activation that can result in thrombus formation. Fibrin and platelets are deposited in stent struts early after implantation. If the endothelium does not reform over the stent struts and/or the structural components, this can lead to further arterial injury resulting in restenosis. Restenosis occurs when vascular smooth muscle cells undergo cell proliferation and migration with subsequent synthesis of extracellular matrix and collagen resulting in neointima formation. Neointimal formation is the major cause of restenosis and can cause in-stent stenosis within months.
Development of tissue-lined stent grafts for arterial occlusive disease is a new and exciting technology. Applying the tissue as the inner lining allows the body to recognize the tissue as its own, thus potentially reducing restenosis. Tissue-lined stents offer an attractive mechanism for quickly treating arterial injuries using minimally invasive techniques and eliminating the long-term sequelae of a foreign body. Tissue-lined stents, like all tissue products for the circulation (e.g., prosthetic pericardial heart valves), must be stored in appropriate preservative solutions (e.g., glutaraldehyde). Storage in such solutions, however, can lead to degradation and loss of tensile strength of the stent.